1) Field of the Invention
The present invention relates generally to agricultural implements and, more specifically, to structure for clearing trash from a narrow area ahead of an opener or similar earthworking tool and for breaking surface crust on soil during planting.
2) Related Art
During planting operations, residue such as wheat straw or corn stalks is often encountered by the furrow opening device on the seeding implement. If the soil is soft or the residue is very tough, much residue is pushed into the seed trench. The residue prevents seed from contacting soil and reduces the opportunity for seed germination and healthy initial plant growth. In heavy residue conditions, trash remaining over the seed or thrown over the furrow by an adjacent device can block sunlight and hinder or even prevent growth of the new plant. Often, a surface crust needs to be broken during planting to assure good emergence, but soil throw must be kept to a minimum to avoid piling too much trash over rows previously planted by trailing openers, to avoid weed emergence problems, and to help keep seed coverage more uniform from row to row.
Different cleaning wheel devices are available including those with long or spoked teeth wheels steered relative to the forward direction to move trash to the side of the row. In certain kinds of straw such as encountered in wheat fields, the straw slips between the teeth and fails to be swept to the side of the row. At times, the straw tends to wrap around the wheel. Depth control is also very erratic with the long tooth design, and the wheel can dig in when soil is loose and ride to high in hard ground conditions. Excessive tillage and soil throw are common with long or spoked teeth, and excessive movement of soil away from one furrow and piling of trash and some additional soil over an adjacent furrow, particularly if high speed planting is attempted, results in less than ideal germination and initial growth of the seeds placed in the furrows. The planting speed of the planting unit can actually be limited by the cleaning wheel structure.
Mounting a cleaning device in the limited space available adjacent an opener has been a source of several problems. Fixed cleaning arrangements which are connected directly to the opener assembly or frame without provision for independent movement are subject to damage if obstacles or other large ground surface irregularities are encountered, and the location of the cleaning device relative to the opener can change detrimentally as the opener follows the ground contour. Pivoting arrangements often fail to track well, and if the cleaning wheel structure is supported closely adjacent the disk opener, the structure can actually hit the opener. Moving the cleaning structure farther ahead of the wheel to avoid interference requires more room than often is available, and as the cleaning wheels are moved ahead there is less holding of the trash close to the soil entry point of the disk so trash hairpins more easily at the disk edge. Supporting the cleaning device in a limited space and providing effective operation without nose-diving or bulldozing of soil during operation have continued to present problems.
A typical cleaning wheel is angled from the forward direction and presents high side loads on the supporting arrangement. If a pivoting arrangement is provided, the high side loads often cause premature bearing failure and can cause the support linkages to bind so good depth control and tracking are lost. The linkages can actually be bent under certain conditions. Providing good side load support for proper pivoting action and long bearing life, without widening the planting unit to the point where narrow row spacings are not available, has been a continuing problem. Clearance under the unit has also been limited by support brackets which project downwardly and catch straw and other debris.